BACKGROUND: Employees with physically heavy work have an increased risk of musculoskeletal disorders leading to reduced work ability. AIMS: To investigate if a high level of musculoskeletal pain or pain-related fear of movement was associated with low productivity among employees with physically heavy work and differing work ability levels. METHODS: The study was conducted at a Danish production site and employees with physically heavy work in the production line were included in the study. Work ability was assessed with the Work Ability Index (WAI), pain-related fear of movement with the Tampa Scale for Kinesiophobia and productivity and musculoskeletal pain by self-reported measures. Sickness absence records for construction of WAI were obtained from the workplace. RESULTS: There was a 77% response rate with 350 employees included in the final analysis. Among employees with only moderate work ability, there was neither an association between pain and productivity nor between pain-related fear of movement and productivity. For employees with good work ability, higher levels of pain and higher levels of pain-related fear of movement both raised the odds of low productivity significantly. CONCLUSIONS: Despite the fact that musculoskeletal pain increases the risk of reduced work ability significantly, musculoskeletal pain and pain-related fear of movement were associated with low productivity only among employees with good work ability.